The present invention relates to a device for dispensing beverages, and more particularly, but not by way of limitation, to improvements on such a device for increasing its drink serving capacity while maintaining or reducing the space occupied and insuring that the beverages dispensed are adequately cooled.
In typical locations where beverages are dispensed, such as in cafeterias and snack bars, the value of counterspace is at a premium. Counterspace in a food serving line is very expensive, especially in larger metropolitan areas. For that reason, beverage dispensing machines are desirably small and compact.
Additionally, it is critical for beverage dispensers to adequately cool dispensed beverages despite frequent use of the dispenser over extended periods of time. One of the most successful methods for accomplishing this objective is to provide a machine which, during periods of non-use, forms an ice bank which slowly melts while cooling the beverages during periods of frequent use. To provide a heat pumping unit which could adequately cool beverages without such an ice bank would put unfeasible power requirements on the unit; the necessary unit would be expensive and oversized.
Typical beverage dispensers employ evaporator coils as part of an electric refrigeration system which forms an ice bank from water placed in a tank. The beverage lines in such a unit are also submerged within the tank to enable cooling of the beverages before dispensing. The water is cooled by ice forming on the evaporator coils, and the cooled water is circulated about the beverage lines by an impeller or other circulating means to cool the beverages to a desired temperature.
The ability of such beverage dispensers to adequately cool during extended period of frequent use depends significantly upon the size and orientation of the ice bank relative to the beverage lines. In fact, since larger ice banks ordinarily take longer amounts of time to melt, the volume of the ice bank formed in such a dispenser is a primary consideration for rating the dispenser. Those factors combined with the degree of insulation provided, the effectiveness of the cooling unit, and the manner of circulation within the cooling tank usually determine the dispenser's ability to adequately operate. To optimize each of those factors while minimizing space is the primary challenge in the technology of beverage dispensers.
Beverage dispensers of this type are also rated by the number of drinks that can be dispensed below a given temperature during a given period of time, and by the temperature of the "occasional drink" (i.e., the temperature of a drink dispensed after the dispenser has not been used for a period of several hours). In the beverage dispensing market, it is desirable that the beverages be dispensed at a temperature of 40.degree. F. or below. A test generally used to determine the maximum capacity of a beverage dispensing apparatus is one determining the total number of twelve ounce beverages that a machine can dispense in a given period of time without exceeding the maximum temperature of 40.degree. F. The occasional drink, which may contain some beverages from lines between the cooling tank and the nozzle, should be maintained below the desired temperature as well.
An example of the above type beverage dispenser is disclosed in the assignee's U.S. Pat. No. 3,892,335, entitled "BEVERAGE DISPENSER" which issued Jul. 1, 1975, and is herein incorporated by reference. That beverage dispenser comprises a tank in which the product lines are positioned in the center and circumferentially surrounded by the evaporator coils. A cooling unit, having a motor driven propeller which extends into the center of the product lines, resides above the evaporator coils. The tank is filled with water to provide the cooling liquid. In operation, an ice bank forms about the evaporator coils, with the water about the product lines remaining liquid. The motor driven propeller rotates to circulate the liquid water about the product lines to produce product cooling.
However, during periods of low use, the ice bank will form such that it abuts both the product lines and the inner walls of the tank. When that occurs, the surface area of the ice bank in contact with the liquid water is reduced, thereby reducing the amount of heat capable of being exchanged between the two. Accordingly, during a subsequent period of peak use, the liquid water is unable to efficiently transfer the heat from the product to the ice bank. As a result, the beverage dispenser produces a limited number of drinks dispensed at a temperature below 40.degree. F. Once the temperature of the dispensed beverage rises above 40.degree. F., the carbon dioxide in solution with the product becomes a gas, which causes the dispensed drink to foam. After the drinks begin to foam, the dispensing capacity of the beverage dispenser has been exceeded.
A second beverage dispenser which provides an improvement over the above dispenser is disclosed in the assignee's U.S. Pat. No. 4,916,910, entitled "LOW PROFILE DRINK DISPENSER" which issued Apr. 16, 1990, and is herein incorporated by reference. That beverage dispenser positions the product lines in the bottom of a tank with the evaporator coils residing above the product lines to form an ice bank. A motor driven impeller is also provided above the product lines to circulate the liquid water. The "LOW PROFILE DRINK DISPENSER" operates similarly to the above beverage dispenser, and therefore, experiences the same problem. That is, during periods of infrequent use, the ice bank forms such that it abuts the inner walls of the tank. Once again, the surface area of the liquid water in contact with the ice bank is diminished. Thus, during subsequent peak use times, the inefficient heat exchange between the product, water and ice bank limits the amount of drinks which may be dispensed at a temperature below 40.degree. F.
Therefore, the present invention has been set forth to provide a beverage dispensing apparatus that alleviates the above problem encountered in the prior art by providing a means for increasing the surface area of the water in contact with the ice bank, thereby increasing the drink serving capacity of the present invention while maintaining the small and compact dispenser size necessary for use in a limited counterspace area.